As wireless communications technologies develop, a communications apparatus of a wireless communications device attracts increasing concern and research. However, in the communications apparatus of the wireless communications device, mutual interference between radio wave beams generated by an antenna array is a main problem to be resolved.
In the prior art, a higher antenna gain and more orthogonal radio wave beams are obtained generally by increasing elements in a sub antenna array (SAA) of an antenna array, so as to reduce mutual interference between radio wave beams. However, research shows that during deflection of the antenna array, a grating lobe does not occur on a radio wave beam generated by the antenna array, only when a distance between adjacent sub antenna arrays is not greater than 0.5λ, where λ is a length of the radio wave beam. However, an increase in a quantity of elements in the sub antenna array results in an increase in the distance between the sub antenna arrays. When the distance between the sub antenna arrays is greater than 0.5λ, during deflection of the antenna array, a grating lobe occurs on the radio wave beam generated by the antenna array. When a distance between the sub antenna arrays is increased, the grating lobe becomes more closed to a main lobe. Consequently, it is difficult to control the grating lobe, and orthogonality of the radio wave beams is affected. The orthogonality of the radio wave beams herein means that radio wave beams in two directions do not interfere with each other. Generally, a radio wave beam has energy in both a required direction and another direction. A most severe case is that a grating lobe occurs. That is, the energy in the other direction is the same as that in the required direction. For example, if a direction of a beam B coincides with a direction of a grating lobe of a beam A, the beam B is completely interfered with. In this case, it may be considered that orthogonality of the beam A and the beam B is poor.
Therefore, how to mitigate a contradiction between a quantity of elements and a difficulty in controlling a grating lobe so as to improve orthogonality of a radio wave beam becomes a problem to be resolved.